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Phobos
Volume 33
Number 7
Contents
1) Meetings.
2) Society News.
3) Guest Speaker.
4) Sky Diary.
7) Autumn Variables..
9) Keeping Abreast.
16) Solar Eclipse.
Ken Willoughby
Ken Willoughby.
Professor David W. Allen.
Derek Hufton.
Melvyn Taylor.
Clive Down.
Melvyn Taylor.
October 2006
Meetings
October Meetings
3rd.
Members Night.
5th. (Thurs.)
Committee meeting.
10th.
'The Chemistry of Interstellar Dust.'
Professor David W. Allen.
16th. (Mon.)
Visit: 7:00pm-9:00pm.
Castleford Ranger Guides.
17th.
The Open University SXR208 Astronomy Course.
Kevin read.
24th.
The November Sky.
Ken Willoughby.
31st.
Open Night. 7:30pm-10:00pm.
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SOCIETY NEWS.
KEN WILLOUGHBY.
September has been an eventful month with speakers. Firstly Sir Arnold Wolfendale came and
talked about 'The Search for Intelligent Life' and secondly Professor Mark Bailey from Armagh
(both at short notice.) Arnold suggested we contacted Patrick with a view to holding an annual
'Patrick Moore Lecture' where we would invite top speakers from all over the World. Patrick
was 'over the Moon' at this and the first of these was on September 26th by Mark Bailey entitled
'New Results and Problems of Cometary Origin.' People are already being contacted for next
year so watch this space..
LEEDS ASTROMEET 2006.
Date: Saturday, 11th November 2006, Doors open 9.00 am.
First speaker 10.00 am.
Last speaker 5.10 pm.
Tickets on door: £10.00
Venue: The Clothworkers Centenary Concert Hall and Foyer, School of Music,
Leeds University (a 300 seat auditorium)
(see venue at http://webprod2.leeds.ac.uk/campusmap/detail.asp?ID=13)
(or a map at http://www.universallyleeds.co.uk//maps/campusmap.pdf)
Speakers:
Tom Boles (BAA)
"Type I Supernovae - the new stars of Cosmology"
Professor John Brown (Astronomer Royal for Scotland)
"The Uncertain Universe - Magic of the Cosmos"
Dr Allan Chapman (Oxford University)
"Mary Somerville and the Lady Astronomer"
Dr Simon Green (Open University)
"Stardust - a new view of Comets"
Nik Szymanek (BAA)
"Photographing the Night Sky"
Trade stalls already confirmed include:
Earth and Sky Books, Aurora Books, Chris Marriott's Skymap, Cape Instruments
Green Witch Telescopes, Opticstar Ltd, British Astronomical Association
Stockport Binocular and Telescope Centre, Astronomica
Further details can be found on the the Leeds Astronomical Society website:
http://www.leedsastronomy.org.uk
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TUESDAY OCTOBER 12TH.
'WE LIVE IN A DUSTY.UNIVERSE!'
PROFESSOR DAVID W. ALLEN.
Following a PhD degree at Keele, and a research fellowship at Cambridge, David
came to live in Dronfield in 1969, when he started work as a lecturer in Chemistry
at the then Sheffield College of Technology, which shortly afterwards became
Sheffield Polytechnic, one of the first of the new ‘Polytechnic’ institutions and
which eventually became Sheffield Hallam University in the early 90’s.
He retired as Professor and Head of Chemistry in 2002, but is still active in the
University as an Emeritus Professor, helping out with the work of a research
group and writing and editing books and other publications. He now has the time
to pursue interests in chemical aspects of astronomy and a bit of scientific
journalism.
3
Sky Diary: October 2006.
Derek Hufton.
Monthly Highlights:
October is a very quiet month for planet watchers. Jupiter is quite low in the west-southwest at
dusk, and Mercury puts in an appearance there even lower, requiring binoculars to find. The
only planet easily visible is Saturn, which is high in the southeast before dawn. The reliable
Orionids meteor shower peaks this month and is favourably placed due to a New Moon at
maximum activity.
Dates & Time:
Sunday 1st October is the 274th day of the year and it is also number 2454009 in the Julian
Calendar.
The Sun:
Rotation number 2049 of Carrington’s series begin on October 18.55 respectively. During the
month the Sun’s axis of rotation is tilted to the east of the vertical some 26.0o at the start of the
month and by month end it will be 24.5o to the east. The Sun’s disk is also tilted away from us
by 6.4o at the start of the month ending the month tilting away from us by 4.4o – crucial data for
you sunspot plotters!
The Moon:
In the Farmers Almanac, the October Full Moon is called the Hunter’s Moon. In other places it
is also referred to as the Blood Moon. However, as the definition of the Harvest Moon is the
full Moon closest to the September Equinox, the title this year goes to the October Full Moon,
occurring 14 days after the equinox – confusing or what? The waning crescent Moon appears a
few degrees to the upper left of Saturn at dawn on the 16th. Back in the evening sky, on the 24th
the thin waxing crescent lies very low in the southwest, well to the left of Mercury and Jupiter.
The next night it is a little higher and farther left of the two planets – but only 4o left of 1stmagnitude Antares.
The Moon's Phases are:
New
Full
22d 05h 14m
07d 03h 13m
1st Qtr 29d 21h 25m
Last Qtr 14d 00h 26m
The Moon is at Perigee (closest approach to the Earth) on October 6th at 14h when its apparent
diameter will be 33’ 26”. Apogee (furthest approach) occurs on October 19th at 10h with
apparent diameter of 29' 26".
The maximum Libration points of the Moon’s ‘wobble’ occur on October 12th and 27th, the
main extra tilt being visible at Position Angles 229o and 42o respectively. This means that you
get a chance to ‘peep round the edge’ of the lunar limb even more on these dates. Remember
that Position Angle is measured from North through East on the face of the Moon (North=0 o,
East=90o, South=180o, West=270o) and it tells you where to concentrate your telescope.
Mercury:
Reaches its greatest elongation of 25o from the Sun on the 16th, shining at magnitude –0.1. This
elongation will be happening very low in the sky at twilight. On the 17th, about 30 minutes after
sunset, you’ll find Mercury just 4o below Jupiter. The two planets are in conjunction in Right
Ascension on the 25th and 28th, with Mercury lower left of Jupiter on both dates. Their very low
altitude will make them difficult to spot..
4
Venus:
Is in conjunction with the Sun on the 27th. Early in the month you might still catch Venus barely
above the eastern horizon before sunrise; then it’s gone.
Mars:
Is in conjunction with the Sun on the 23rd and is therefore not visible this month.
Jupiter:
Is still easily visible as the month commences, shining at magnitude –1.8. It is located low in
the west-southwest in early twilight. By the end of the month it will be so low that you’ll
probably need binoculars to locate it.
Saturn:
Rises in the northeast at around 3am, shining at magnitude +0.5, at the start of the month. By
the end of the month the planet rises just after midnight. The best time for observing will be just
before dawn, when Saturn is high in the sky and is much more likely to show a steady and sharp
image. The rings are now tilted by only 13o.
Uranus and Neptune:
Are both well up by mid-evening, in the southeast and south respectively. Uranus will be
shining at magnitude +5.8 with Neptune somewhat dimmer at +7.9. Check out the Sky &
Telescope website (http://skytonight.com/observing/objects/planets/3311356.html) or the BAA
Handbook for finder charts.
Meteor Showers:
The major shower active this month are the Piscids, Orionids and Taurids. The Piscids is
another multiple-radiant ecliptic complex with low rates. The Orionids, associated with Comet
Halley, usually has fast meteors with a high proportion of persistent trains. The shower has a
flat maximum with several sub peaks and is favourable this year. By contrast the Taurids has
slow meteors, often bright, but not the rich fireball source suggested in some books. It starts
activity this month, although doesn’t peak until early November. Full details as follows:
Shower
Limits
Maximum
 RADIANT 
ZHR RA
Dec
Piscids
Sep-Oct
Oct 13
?
01h 44m
+14o
21 days
Orionids
Oct 16-27
Oct 20
25
06h 24m
+15o
28 days
Taurids
Oct 20-Nov 30
Nov 3
10
03h 44m
03h 44m
+14o
+22o
13 days
5
Moon
at Maxm.
6
Looking South from the observatory @ 22:00h on October 15th.
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A Selection of Autumnal Variables.
Melvyn Taylor.
Stars from magnitude 2 to 10.
Eta Aquilae:
Discovered by Edward Pigott (York) in 1874 this easily found Cepheid variable lies under
Altair and changes from mag. 3.5 to 4.4 every 7.17days. Comparison stars beta Aql mag. 3.21
and iota Aql at mag. 4.36 are very useful. This young, large star changes its temperature and
surface area with regularity.
RZ Cassiopeiae:
An eclipsing binary in a binocular field of iota Cas varying from mag. 6.2 to 7.7 in the orbital
period of the system, 1.195 days. The total duration of an eclipse is 4.8h. The star is predicted to
be faint at one of its primary minima on Oct 02d at 20.8h (UT). Over long intervals the period
of the system changes by about 15 minutes.
Mira (omicron Ceti):
This infamous variable probably first recorded to be changing by Fabricius in 1596 lies 420
light years away. During October the star is nearing a minimum about mag. 9 to 10. Its extreme
mag. range is 2.0 to 10.1 in a period of 329 days. This is a huge star having its disc imaged at
0.048 arc seconds, corresponding to a diameter of around 6 astronomical units (450 million
kilometres). Not far from delta Ceti.
AF Cygni:
The star is a typical semi-regular giant star which has been catalogued varying from mag. 6.4 to
8.4 with a mean period of 94d. Interest in these type stars is that the period is often poorly
expressed and it may vary slowly, become irregular or may show at a constant brightness. It is
probably best found by its location near delta Cyg.
RY Draconis:
A typical semi-regular variable star that is circumpolar and relatively easy to find being in a
triangle of bright stars labelled 7 , 8 and 9 Draconis. The overall changes are from mag. 6 to 8
with a dubious period of 172 days. All that is required is a small binocular and clear skies!
AG Draconis:
A star in outburst at present and around magnitude 8.5 or thereabouts; at its quiet times visual
mag. 10.0. It is an unusual eruptive binary object (known as a symbiotic) with a recent active
phase when it was in outburst for 5 years from 1981. Being circumpolar from the UK at
declination 67* the star is in a relatively bland area between the brighter stars of the Little Bear
and the curving Dragon.
UW Herculis:
Easily found near pi and rho Her (the left/east shoulder of the Giant) using a binocular this
semi-regular variable has recently livened and is showing its period of about 100d with a
brightness factor change of about 2.3 (mag. 7.8 - 8.7).
alpha Herculis (Rasalgethi):
One of the largest stars known but W.Herschel did not know that when he discovered its
variability in 1795. It is a semi-regular, reddish, looking naked-eye star that shows slow
brightness changes. There are 3 stars that show the combined light some 380 light years away.
It is about mag. 3.3 at present.
8
Sheliak (beta Lyrae):
One of the most observed and researched stars in the sky. John Goodricke discovered the
changes from York (1784) and his explanation was that one star was being eclipsed by another
in co-orbit. With the naked-eye the changes are from mag. 3.3 to 4.3, the star having deeper
fades every 12.94d. In between there is a lesser dip to mag. 3.8. Sheliak has a luminosity 2600
times that of our Sun, it is 900 light years away. Gamma Lyr is mag.3.23 and kappa Lyr 4.34 convenient comparisons.
X Ophiuchi:
Dscovered by the Rev'd T. Espin in 1886 this long period variable (6.6 to 8.8, period 329d) is
similar in nature to Mira and frankly not easy to find. But once found its location is easily
remembered since it is adjacent a small triangle of bright stars with a mag. 5.4 star to its west in
the same small field of view.
GO Pegasi:
A few degrees from alpha Pegasi (Markab) this "red" looking star changes from about mag. 7 to
8. The star is in a class of evolved giant stars with no charted periodicity in its light variations.
Algol (beta Persei):
Ane of the most famous stars stars in the sky with an intriguing name. The name has been
translated as the Demon Star associated with the eye of the Gorgon, Medusa, within the
mythology tales of the hero Perseus. It is likely that Montanari first recorded the star's
variability in 1667 yet John Goodricke in 1782 investigated a continuous series of its changes
and came to the explanation of these as an eclipse in a system of stars. This is the first eclipsing
binary star recorded and it provides a long base-line for understanding period changes and how
stars in close proximity interact. The distance between the main stars is only 0.07 astronomical
units (26 times Earth to Moon). The star is predicted to be faint at a primary minimum on Oct
19 at 22.4h and at other intervals of its period 2.867d. It changes from mag. 2.1 to 3.4. A host of
bright comparison stars are nearby but rho Persei, the nearest is also a variable so it is wise not
to use this.
HU Tauri:
A star in a similar mould to Algol an eclipsing binary not far from Aldebaran (alpha Tauri).
Using a binocular the object varies mag. 5.5 to 6.9 every 2.05 days with the eclipse lasting at
total of 7.7 hours.
V Ursae Minoris:
This is not that easy to find since care is needed as the object is one of 4 in a near line that may
be easily confused. In the last few years this semi-regular has moved out of a long irregular
phase and is now showing strong variations from 7.2 to 8.8 in a period of about 72 days.
Observations by the writer using small binoculars of some of these objects are summarised in
the light curves. Most of these variable stars are to found by reference either to planetarium
software or star charts, for example, Atlas of the Night Sky, 2005, Collins. Charts giving
comparison stars and magnitudes may be obtained in paper from the writer or by reference to
the BAA variable star section web pages:
http://www.britastro.org/vss
[Data: General Catalogue of Variable Stars; location charts: AAVSO]
MDT 2006 August.
9
KEEPING ABREAST.
CLIVE DOWN.
HUBBLE FINDS PLANET'S STELLAR COMPANION
STSI
The Hubble space telescope has for the first time identified the parent star of a distant
planet discovered through gravitational microlensing.
Microlensing occurs when the
gravitational field of a foreground star amplifies the light of a background star that momentarily
aligns with it. The particular character of the light magnification can reveal clues to the nature
of the foreground star
and any associated planets. However, without identification and
characterization of the foreground star, little can be said about the accompanying planet.
The newly discovered host star, catalogued as OGLE-2003-BLG-235L/ MOA-2003-BLG53L, has a planetary companion that was discovered in 2003 through ground-based
gravitational micro-lensing. A planetary companion of a foreground star can produce additional
brightening of the background star. The additional brightening can reveal the planet, which is
otherwise too faint to be seen by telescopes. The Hubble images allowed the research team to
resolve the background source star from its neighbours in the very crowded star field in the
direction of the centre of our Galaxy.
The star appeared to be about 20% brighter than expected; the additional brightness is most
likely from the foreground lens star, which hosts the planet. Hubble could not resolve the two
stars, but, by taking multiple images through differently-coloured filters, it recorded a colour
offset in the overlapping images of the two stars. That is possible because the foreground star is
redder than the background star. From its colour, the researchers were able to make a crude
estimate of the type of the star, and thereby obtain its distance as 19,000 light-years and the
planet's mass as 2.6 Jupiter masses. The characteristics of the lensing event show that the planet
is in a Jupiter-sized orbit around its parent red star.
10
CHANDRA CONFIRMS HUBBLE CONSTANT
Chandra X-Ray centre
A critically important number that specifies the expansion rate of the Universe, the socalled Hubble constant, has been independently determined by the Chandra X-ray Observatory.
The Hubble constant is calculated by measuring the speed at which objects are moving away
from us and dividing by their distance. The usual methods of estimating it rely upon measuring
the apparent brightness of standard objects whose absolute luminosities ('candle-powers') are
known and are supposed to have remained constant throughout the age of the Universe.
Optimist have thought in recent years that the value of the constant is known to about 10%, at
72 +/- 8 km/s per megaparsec. Now, by a combination of X-ray data from Chandra with radio
observations of galaxy clusters, distances have been estimated to 38 galaxy clusters ranging
from 1.4 to 9.3 billion light-years. The results give a Hubble constant of 77 km/s per
megaparsec, with an uncertainty of about 15%, thereby reinforcing other recent values. The
implied age of the Universe is between 12 and 14 billion years.
ANOTHER STORY
Ohio State University
Certain astronomers have suggested that the Triangulum Galaxy (M33), or at any rate one
binary-star system in it, is about 15% further away from us than has been thought. That would
imply that the Hubble constant should be correspondingly reduced and that the Universe could
be 15% bigger and older. The astronomers studied two of the brightest stars in M33, the
components of a binary system in which one star eclipses the other every five days. They
determined the masses of the components, and from that they guessed the candle-power of
those stars. Then the comparison between the intrinsic brightness and the apparent brightness
told them how far away the stars were. It was 15% further than they expected, about 3 million
light-years. The margin of error was claimed to be 6%, but there might be merit in waiting a
bit before
altering the Universal distance scale to suit the findings on one binary system; the
star's masses may have been determined quite accurately, but their luminosities are only
conjectural.
BINARY PLANET-LIKE OBJECT
BBC News
Astronomers at the University of Toronto have discovered a companion to a 'planetary-mass
object' or orphan planet -- one that has no star around which to orbit. Both objects have masses
similar to those of extra-solar giant planets, usually found in orbit around a star. The
researchers discovered the companion candidate in an optical image taken with ESO's 3.5-m
New Technology Telescope on La Silla, Chile,and investigated it further with the 8.2-m Very
Large Telescope on Paranal.
Those follow-up observations confirmed that both objects are young, at the same distance, and
much too cool to be stars. From theoretical models, the astronomers estimate that they have
about 14 and 7 times the mass of Jupiter.
The newborn pair, barely a million years old, has a separation about six times the distance
between the Sun and Pluto, and is located in the Ophiuchus star-forming region approximately
400 light-years away. It is the first planetary-mass object to be resolved into a double. The
existence of such a wide pair with such a small total mass and consequently weak gravitational
binding sets useful constraints on theories of their origin.
11
GLIMPSES OF OBJECTS BEYOND NEPTUNE?
New Scientist
Astronomers combing through 89 hours of observations from the Rossi X-ray Timing
Explorer think that they detected 58 minuscule trans- Neptunian objects (TNOs) between 20
and 100 metres in size. What the astronomers actually saw in the records, which were all of a
distant X-ray source called Scorpius X-1, were sudden momentary dips in the X-ray brightness.
The best idea that they could think of by way of explanation was that the dips, which mostly
lasted only 2 or 3 milliseconds, were caused by transits of TNOs, which would be only of the
order of 50 metres across if they were at the assumed distance of 43 Astronomical Units. Such
objects would be much too small to detect directly with any telescope. If there were really so
many of them transiting a very small X-ray source, the total number of such objects would
have to be very formidable.
1000nth SUNGRAZING COMET FOUND BY SOHO
Science Daily
There is no formal definition of a 'Sungrazing comet,' but the term typically refers to the
Kreutz-group comets, which have a perihelion distance of less than 0.01 of an Astronomical
Unit. The 1000nth Sungrazer is the 1185th comet discovered in data from the SOHO LASCO
or SWAN instruments (the other 185 are not members of the Kreutz group). The faint object is
officially designated C/2006 P7 (SOHO) by the Minor Planet centre of the International
Astronomical Union. Before the launch of SOHO in 1995 December, only some thirty
members of the Kreutz group were known. All 1000 Kreutz comets are believed to be
fragments of a single great comet observed in c. 371 BC by Aristotle and Ephorus, and the
fragments themselves continue to
fragment, making more Sungrazing comets.
20% OF MATTER USED UP
Australian National University
The Universe has used up about 20 per cent of its normal matter, or original fuel reserves,
according to findings from a survey of the 'nearby Universe' by an international team of
astronomers involving researchers at the Australian National University. The survey suggests
that about 20 per cent of the normal matter or fuel that was produced at the Big Bang 14 billion
years ago is now in stars, a further 0.1 per cent lies in dust expelled from massive stars (and
from which solid structures like the Earth and its people are made), and about 0.01 per cent is in
super-massive black holes. The survey data, which constitute the 'Millennium Galaxy
Catalogue', were gathered by telescopes in Australia, the Canary Islands and Chile, and include
over ten thousand giant galaxies. According to the survey leader Dr Simon Driver of St
Andrew's University, the remaining material is almost completely in gaseous form lying both
within and between the galaxies, forming a reservoir from which future generations of stars
may develop. The catalogue has estimates of the
distribution of each galaxy's stars between
its central bulge and its surrounding disc-like structure. Roughly half of the stars appear to
reside in bulges and the other half in discs.
FOUR NEW MILKY WAY SATELLITES
New Scientist
Four new satellite galaxies of the Milky Way have been discovered, bringing the total
known to about 20. The pace of new discoveries suggests that many more such satellites
remain unknown. The satellites are dwarf galaxies a few hundred to a few thousand light-years
across. The tiny galaxies are thought to be the building blocks of large galaxies, such as our
own Milky Way which is about 100,000 light-years across.
12
The small galaxies are faint and difficult to observe behind the throngs of foreground stars in
the Milky Way. Just two years ago, only 10 satellite galaxies were known, with the exact
classification of some objects in dispute. Now, thanks to new observing techniques and detailed
sky maps such as the Sloan Digital Sky Survey (SDSS), that number has doubled. Astronomers
use SDSS to look for the particular types of stars expected to lie in dwarf galaxies, then detect
the dwarfs as slight 'overdensities' of those types of stars. The four new discoveries were made
by astronomers at the University of Cambridge. Named after the constellations in which they
were found -- Coma Berenices, Canes Venatici II, Hercules, and Leo IV, all of them are
between roughly 100,000 and 500,000 light-years away. The largest and smallest are Hercules
and Coma Berenices, which are about 1000 and 200 light-years across, respectively. Like most
of the other dwarfs discovered by SDSS, the new finds are much smaller and fainter than the 10
dwarfs that were known previously.
HIGH-ALTITUDE CLOUDS SEEN ON MARS
Science Today
Until now, scientists had been aware only of the clouds in lower reaches of the atmosphere.
Mars Express has now seen a fleeting layer of clouds, most likely composed of carbon dioxide.
at an altitude between 80 and 100 kilometres. The new high-altitude cloud layer may have
implications for landing on Mars, as it suggests the upper layers of Mars' atmosphere may be
denser than was previously thought. That will be an important piece of information for future
missions if they rely on friction in the outer atmosphere to slow down spacecraft (a technique
called aerobraking), either for landing or going into orbit around the planet.
SUPERNOVA CAUGHT IN THE ACT
Astronomy.com
A weak but abnormally long-lasting gamma-ray burst (GRB) has given astronomers an
unprecedented start-to-finish view of an exploding star. Ground- and space-based telescopes
studied the blast in detail at gamma-ray to radio wavelengths. Scientists now suspect that such
weak bursts may outnumber more powerful ones by as much as 10 to 1. Usually, such events
are not detected until after the supernova has brightened substantially at optical wavelengths,
many days after the initial explosion, but on this occasion astronomers were able to study the
remarkable event from the very beginning. On February 18, the Swift satellite sensed a rise in
gamma rays from the constellation Aries. Within 20 seconds, the spacecraft reported the burst's
location to astronomers and slewed its instruments towards the source. The burst lasted about
35 minutes -- about 100 times longer than typical bursts associated with supernovae. It was
also just 1 per cent the brightness of GRBs seen in the distant Universe, which places it in a
sub-class known as X-ray flashes. After two-and-a-half minutes, Swift's telescopes identified
the blast's X-ray and ultraviolet counterparts. They coincided with a dwarf galaxy about 500
million light-years away. That places the burst some 25 times closer than typical GRBs. On
February 20, two days after the GRB, a brightening type Ic supernova began to be seen.
IMPACT LANDING ENDS SMART-1 MISSION
ESA
A small flash was detected on the Moon as the SMART-1 spacecraft crashed into it on the
night of September 2. The impact took place in an area of the Moon in the vicinity of Lacus
Excellentiae,
unilluminated by the Sun but near the terminator, at a grazing angle of between
5 and 10 degrees and a speed of about 2 kilometres per second. The planned impact concluded
a successful mission that, in addition to testing innovative space technology, had been
conducting a thorough scientific exploration of the Moon for about a year and a half.
13
SATELLITES COULD NAVIGATE BY X-RAY STARS
New Scientist
Future satellites could use X-ray-emitting stars, rather than GPS signals, to get their
bearings, according to plans by the US military. X-ray navigation technology would be less
vulnerable to enemy interference than GPS, and could also be used far from Earth to help
interplanetary space probes keep track of their positions. The X-ray beacons would be pulsars,
rapidly spinning stars which emit regular pulses of X-rays as they spin. Each pulsar has a
unique frequency and
location in the sky. Locking onto any one of them would tell the
satellite which direction is which in the sky. The signals from several pulsars could be
exploited to determine a spacecraft's
position and velocity in the same way as by GPS, but in
principle it would be simpler because the beacons are fixed. The pulsar signals are ideal for the
purpose, because their frequency stability rivals that of atomic clocks. A further useful feature
of the system, from a military point of view, is that X-ray detectors are not easily blinded by
lasers which might be aimed at them maliciously, nor by being pointed accidentally at the Sun,
unlike the visible-light cameras used to track ordinary stars.
BIG BANG'S AFTERGLOW FAILS SHADOW TEST
Science Daily
The apparent absence of shadows where shadows were expected to be is raising a question
about the faint glow of microwave radiation that has been regarded as proof that the Universe
was created by a 'Big Bang'. In a finding sure to cause controversy, scientists at the University
of Alabama found a lack of evidence of shadows from 'nearby' clusters of galaxies in new,
highly accurate measurements of the cosmic microwave background. A team of scientists used
data from the Wilkinson Microwave Anisotropy Probe to scan the microwave background for
shadows caused by clusters of galaxies.
IIf the background really originated in the Big Bang fireball, then it should appear to come from
further away than anything else that is observable, and massive clusters of galaxies should all
cast shadows on the background. The principle of shadowing is elementary: if you see a
shadow from a cluster, it means that the radiation comes from behind it, but if you don't see a
shadow, then you have something of a problem. Among the 31 clusters that were studied by the
team, some appear to show a shadow effect and others do not. Taken together, the data show a
shadow effect about one-quarter of what was predicted -- an amount roughly equal to natural
variations previously seen in the microwave background across the entire sky.
14
MARS ROVER NEARS CRATER
NASA
The Mars rover Opportunity is closing in on what could be the richest scientific findings of
its mission so far. Within the next week the robotic geologist is likely to reach the rim of a
crater bigger than any it has previously visited. The crater, known as Victoria, is approximately
750 m in diameter and 70 m deep. Images from the Mars Global Surveyor orbiter show the
crater walls to expose a stack of rock layers approximately 30 to 40 metres thick. Opportunity
will send back its initial view into the crater as soon as it gets to the rim, and its controllers hope
to use its observations from various points around the rim to try to plot a route for it to enter the
crater. The twin rovers have been exploring landscapes on opposite sides of Mars since 2003
January. Originally, their missions were supposed to last three months, but both are still
investigating Mars' rocks, soils and atmosphere after more than ten times as long. Opportunity
works in a region where rock layers hundreds of metres in thickness cover older, heavily
cratered terrain.
PLANET OR FAILED STAR?
STSI
Astronomers using the Hubble telescope have photographed one of the smallest objects
ever seen around a normal star beyond our Sun. With 12 times the mass of Jupiter, the object,
CHXR 73 B, is small enough to be a planet, but it is also massive enough to be a brown dwarf,
a failed star. There is at present no consensus on how to decide which objects orbiting other
stars are truly planets. Hubble discovered the object while conducting a survey of isolated
brown dwarfs. CHXR 73 B is 19.5 billion miles from its red-dwarf primary, roughly 200 times
farther than the Earth is from the Sun. At 2 million years old, the star is very young when
compared with the Sun. Young brown dwarfs are brighter than older, cooler ones, so they can
be seen at lower masses, where older dwarfs would be undetectable. Hundreds of brown dwarfs
have been found in our Galaxy since the first ones were discovered about a decade ago. Most
of them are alone in space and not orbiting stars.
There is interest in studying young star systems in an effort to understand how small bodies
formed. Planets are supposed to form in circumstellar discs of dust and gas, but such discs are
normally not big enough to cover the region in which CHXR 73 B is seen; even if the red-dwarf
primary possesses a disc there would not be enough material at that distance from it to create a
planet. Theoretical models show that giant planets like Jupiter form no more than about 3
billion miles from their stars.
PLUTO ASSIGNED A NUMBER AND XENA RENAMED ERIS
Space.com
Pluto has been given a new name to reflect its new status as a dwarf planet. On September
7, the former 9th planet was assigned the asteroid number 134340 by the Minor Planet Center.
The move gives_expression to the International Astronomical Union's recent decision to strip
Pluto of its planethood and place it in the same category as other small Solar-System bodies
with accurately known orbits. Pluto's satellites, Charon, Nix and Hydra are considered to be
part of the same system and will not be assigned separate asteroid numbers, according MPC
director emeritus Brian Marsden. Instead, they will be called 134340 I, II and III, respectively.
There are currently 136,563 asteroid objects recognized by the MPC; 2,224 new objects were
added last week, of which Pluto was the first.
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The name Xena by which the body formally designated 2003 UB313, whose size (slightly
larger than Pluto's) precipitated the recent concern over the definition of planets, is another
casualty of recent IAU decisions -- the object has been assigned the asteroid number 136199
and officially named Eris. Eris is the Greek goddess of discord, so the name hints at the
troubled ordination of the newly-discovered body. One of Eris' discoverers, Michael Brown of
the California Institute of Technology, said that the new name was "too perfect to resist". Eris'
moon has been named Dysnomia, after Eris' daughter -- the spirit of lawlessness -- in Greek
mythology. Eris joins Pluto and Ceres in the new category of 'dwarf planets.'
Six Months On ... and the Sun is still there!
It is coming up to 6 months from the 2006 total Solar eclipse March 29) so the memory bank is
being returned to.
This was a cruise in the Med. taking in a wealth of archaeology on the way to Libya. There
were several friends and colleagues on board the MV Perla together with some 770 others. But
why do "experienced, hard-bitten" astronomers, amateur and professional alike go for the few
minutes or even seconds of the darkening of the Sun? My first experience of 1991 July 11 may
be likened to train-spotting/knocking off a "first" event. This tear-dripping event of the Black
Moon surrounded by the Sun's corona was seen from the tip of the Baja Peninsula, San Jose del
Cabo. A total Solar eclipse is virtually indescribable in words and one of the best attempts I
have read is from a late 1991 Sky & Telescope - moving stuff. Solar totality is likened to a
spiritual event, it is certainly primeval in perception. Several who were shattered not to view the
1999 Aug 11 totality due to cloud cover may have been impressed by the apparent midnight
conditions during daylight hours but the dark side of the Moon and the solar atmosphere were
absent.
Back to the near 800 passengers on route for the darkness. At Manchester Airport and thrown
into the chaos of a "punch-up" with a crazed thug we then met with more polite types, other
astronomers from local societies and professionals like the WYAS President Prof. David
Hughes. Later on board the MV Perla moored at Heraklion (Crete) we came across lots of other
friends and acquaintances from all over the UK. One of my long standing variable star friends
Dr. Rhona Fraser (Inverness) dashed around a corner with Jill, her cabin mate, and soon the
chat became completely irrelevant to other non-vs orientated types. There were a few "strange"
astro creatures, those who could be the subject of one's nightmares or part of an Alice Cooper
clan. (Apologies to any fans thereof).
Eclipse day started with a 02h ship's awakening then a departure from Benghazi harbourside on
coaches (23 in total) for a 500 mile trip to the observing site close to the ground centre-line in
the Jula Oasis. Stress, trauma, paranoia, expectation - anxiety, deep seated "rumbles" - please
reader, try and relate to one who has shunned away from long distance coach travel since he
said 20 years ago he would never use this form of transport. But it was impossible not to
participate in this Libyan and Greek expedition if totality was to be seen. Cornwall 1999 was a
sombre reminder of disappointment and failure. Things and folks go through the mind as it
plays tricks in deserts - flat, boring ochre sand for miles and miles, the optical lake near the
horizon, another jolt as the Egyptian (El Joker company) coach suspension clattered over
another dead camel. No, I joke, but this is an attempt at conveying reality. The eclipse team did
their best to eat, part sleep and keep each other in the right frame of mind. Mark chats about his
last holidays in Europe, Jill relates her enjoyment of opera, "Einstein on the Beach" seems
relevant, Rhona discusses recent intricacies of a variable star, Alex and Harry my walking
chums of many years hark back to happier times in a sodden tent on a Glencoe trip!
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Anything to pass the time comfortably, audio tapes played, cameras checked, another doze is
broken up as the driver honks to a fellow coach - a mindless tune like "Close Encounters speak" from one alien to another? It is also the tiny event that picks up the spirit. At a service
station toilet stop where all the coaches had to refuel again, we lined up waiting for the long
"loo" line. The small cafe area had a cooler with Pepsi bottles - and cans of "Booze" - in
Libya!? Some of the party could not resist. Would the security put us in the local "clink", I think
not. Part and parcel of the Libya tour and not only the eclipse site involved keeping people safe
and politics insisted we had proper armed security with several X-Men look-alikes hounding
around. So the convoy of coaches had police trucks at front and rear, if one coach had to refuel
or break down, the convoy had to stop. At major road junctions of which there were few the
main road was blocked by another police/army crew, and through small towns nearer Benghazi
police were showing a presence. Our coach no. 13 broke down so we had to use the spare one,
an equally dismal El Joker.
With several other delays on the outward trip the tented, international site was not reached since
the road was blocked by a multitude of other vehicles and camels, traders, military and the
Brits! Helicopters hovered in the distance into the huge site, TV company wagons were
extremely modern in comparison to other transportation. Where was Kate Adie and her team?
We had been asked not to show any obvious cultural allegiances in the form of flags or logos but I did wear my Yorkshire CCC sunhat!
About 1.9 km short of the area that Explorers had defined for the observation site, and with only
20 minutes to go for first contact, most of the 800 quickly took themselves off into a once virgin
sand 'scape now littered with cars, trucks, assorted astronomers and other eclipse cases, it had
the air of a rock festival. And a countdown was now on for the main players were coming to the
stage. Describing a total eclipse in words is very hard but John Mason's pre eclipse account was
magnificently near the actuality - the man is a minor genius! An eerie shimmering on the sand
as thousands of dark sinuous snakes washed their way prior to first contact - shadow bands. A
superb diamond ring broke out near a set of Baily's Beads with the pink prominence at about
11o-clock. The five or so coronal streamers to the left, three to the right, in binocs a review of
magnetic strewn hairs from the polar areas and Venus plus Mercury in the twilight dark sky.
And the Dark Circular Hole that is the Moon in a unique situation. People gasping, people
praying folk just in silent awe. Others recorded a personal record in one's experiences. On the
Moon's departure a host of pink prominences and a wonderful double diamond and shadow
bands yet again. Wow! and biting of lips! The 4 minutes of totality was worth the effort and
hardship, then 8.5 hours on the journey back to the boat was similar if more desperate than the
outward leg.
Photos had been taken, happy snaps of our eclipse site and observers, brief encounters with
Libyans who had travelled to the site. I had shown a bunch of lads the partial phases which they
photo'd using a mobile through my visual scope. Rhona had been presented with a gift of an
embroided gold coloured hat made by the group who had been praying nearby. Mark had lit up
his celebratory cigar, Harry talked with local scouts who unbelievably had heard of Liverpool
FC, probably not of Doncaster FC. Alex announced that this had been one of the best eclipses
he had seen. Ray and Chris were happy and smiling not that far away; the Marchant family
were not in sight to be asked "how was it for you?". Back on the ship the day after, this question
was asked and answered many times. Other astronomers on site were really too happy to be true
as they started packing away the kit and chatting over the spent scene. Several whose first
successful total eclipse this was like Jill stayed for the whole partial phases - quite right.
The eclipse day had taken 23 hours when the cabin door was opened and sleep came easy.
Wednesday 2006 March 29 in the Libyan Desert, a tiring but very special day.
Melvyn Taylor, 2006 April and September.
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